title: Control of ribosomal subunit rotation by elongation factor G.
abstract: Protein synthesis by the ribosome requires the translocation of transfer RNAs and messenger RNA by one codon after each peptide bond is formed, a reaction that requires ribosomal subunit rotation and is catalyzed by the guanosine triphosphatase (GTPase) elongation factor G (EF-G). We determined 3 angstrom resolution x-ray crystal structures of EF-G complexed with a nonhydrolyzable guanosine 5'-triphosphate (GTP) analog and bound to the Escherichia coli ribosome in different states of ribosomal subunit rotation. The structures reveal that EF-G binding to the ribosome stabilizes switch regions in the GTPase active site, resulting in a compact EF-G conformation that favors an intermediate state of ribosomal subunit rotation. These structures suggest that EF-G controls the translocation reaction by cycles of conformational rigidity and relaxation before and after GTP hydrolysis.
authors.affiliation: Department of Molecular and Cell Biology, California Institute for Quantitative Biosciences, University of California, Berkeley, CA 94720, USA.
authors.forename: Arto
authors.initials: A
authors.lastname: Pulk
authors.forename: Jamie H D
authors.initials: JH
authors.lastname: Cate
mesh_terms: D018360:Crystallography, X-Ray; D004926:Escherichia coli / Q000201:enzymology*; D006160:Guanosine Triphosphate / Q000737:chemistry*; D006868:Hydrolysis; D008954:Models, Biological; D020653:Peptide Elongation Factor G / Q000737:chemistry*; D014176:Protein Biosynthesis; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000737:chemistry; D012343:RNA, Transfer / Q000737:chemistry; D054681:Ribosome Subunits, Large, Bacterial / Q000737:chemistry*; D012399:Rotation
chemical_list: D020653:Peptide Elongation Factor G; D012333:RNA, Messenger; D006160:Guanosine Triphosphate; D012343:RNA, Transfer